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Clear Solar Panels Double As Projection Screens
EnergyEfficient writes "Metropolis Magazine has an article about a company that is producing transparent solar panels. The panels 'can generate 3.8 watts of electricity per square foot, an above-average level of efficiency.' They come in a thick version that can be used for glazing buildings. Imagine if all those glass skyscrapers could also produce power! As an interesting aside, they can also be used as screens for projection TV units."
Let's take a super-skyscraper, assuming a 200' square base that's as high as the Sears tower (roughly 1450' to the roof top). Assuming the building maintains its rectangular cross section from the ground to the top gives us an area of 1.16 million square feet which would generate ~4.4 megwatts of electricity, which is a lot of electricity.
The article calls out a price of $45 per square foot, making the solar panels for such a building cost about $52 million dollars. Surprisingly cheap for that much electrical capacity, though the usage factor would be pretty low, what with it being dark at night and all.
"producing transparent solar panels."
"As an external glaze, PV-TV allows up to 10% visible light to be transmitted through the panel."
transparent Audio pronunciation of "transparent" ( P ) Pronunciation Key (trns-pârnt, -pr-)
adj.
1. Capable of transmitting light so that objects or images can be seen as if there were no intervening material. See Synonyms at clear.
" Wait, how much do the super-efficient panels cost? Oops..."
A.) Prices will go down if these things take off.
B.) Think of how much cheaper the electric bill will be. (Also consider how much more regular it has the potential to be.)
C.) Imagine if an ill-timed power outage wouldn't necessarily mean the building was affected.
I imagine once somebody sits down with a calculator and thinks out 5 to 10 years, the cost will end up being quite competitive AND they get bonus features to boot.
Just because something starts out at a high price doesn't always mean the value's not there, or that the price will always stay that way. The main reason I'm replying is not so much because of your particular comment, but because I've seen a great deal of sticker-shock on Slashdot without understanding some of these basic things about how technology economics works.
"Derp de derp."
As for ethanol, I will raise you Cornell study with this one from the USDA which seems to say that ethanol is energy positive.
http://www.windmeadow.com/
be lucky to get the things to last 5 years without breaking), then that momentary expenditure of oil will more than pay for itself.
Um, solar panels do in fact last that 20-30 years.
I don't care if it's 90,000 hectares. That lake was not my doing.
The article states that the factory where the glass is made is also the largest user of the glass:
The factory is now the world's largest single PV module plant, producing 100 megawatts of energy annually.
A megawatt isn't a unit of energy, it's a rate of transfer. Do they mean that it produces a continuous flow of 100 megawatts? If so, they would have to have 604 acres of glass (2.4 million of their 1m^2 panels). Of course you need to double that number because they're only collecting power half the day (generously assuming they're at peak output during all daylight hours)
On the other hand, if they're talking about generating 100 megawatt hours over the course of a year, then the plant is generating about 11,000 watts, or enough for about 10 average homes. By those numbers they'd have about 600 panels. That's a lot more reasonable.
Kevin Fox
I think the question most businesses ask is how long will it take to get a return on investment.
The manufacturer specifies 38 W/m^2 or about 3.5 W/ft^2. Used as a window, the orientation would be fixed and I think you would be lucky to get four hours of good light to get something close to full efficiency.
So 3.5*4 = 14 Wh per day.
If electricity is 15 cents/kWh, you could buy 300 kWh for $45 (the cost per square foot of window).
To produce 300 kWh from a square foot of window would take 300 000/14 = 21 428 days or roughly 59 years.
Of course that doesn't take into account connecting your windows into the buildings power and the loss of effieciency there. And I also didn't take into account what the cost of regular windows are to begin with, since that should be reduced from the price, but I would guess they would be a few dollars and might take 10 years off the total.
Once electricy prices increase to $1.50/kWh these babies should be selling like hotcakes.
purves
Don't forget that the sun won't hit all 4 sides of the bulding. With the angle of incomming light, and the position of the sun during the day/season, you'd be lucky to get even a third of your calculated total electricity produced.
My Kyocera KC120 panels produce 12 watts per square foot, 3.8 doesn't sound above average to me.
3.8 Watts per square foot is a joke. Your average silicon panel (~10% conversion efficiency) is 4 times more efficient. Triple junction panels are 3 times better than that.
http://jsl.com/solar
Polycrystalline cells don't have this problem, and I can buy top shelf "BP Solar" branded cells with a 20 year warranty! Similar $/Watt too. What does this mean for the MSK-clad building? Will its enviro-friendliness fade? And what effect does age have on its transparency/opacity?
And how much energy does it take to produce a single square foot. There is a basic falicy that a lot of folks seem to miss ... The same thing holds for all current forms of solar energy.
Actually, this is a basic falacy that you have missed. While what you say is true for ethanol, it is not true for modern photovoltaics (and hasn't been for some time). As for photothermal, you are also dead wrong.
Do all four sides of the sears tower get direct sunlight? How many hours of full sunlight? The generating numbers for photovoltaic panels are always full sunlight output. Notice in the article how only the top and one side (the south side in the nothern hemisphere) is clad. Aiming photovoltaics east or west or north is not cost effective.
I gotta look at my 165 W sharps which are about 8sq feet and wonder at that. But my panels are not clear. Which is a plus as the also shade the roof and make that part of the house cooler. (if only they had 1/2" pipes wired under them so I could water cool them and run the warmed water into a tank).
And yes, the windows are mounted vertically. In math, that's at 90 degrees.
The ideal mounting angle is your latitude (eg the Bay Area and DC are around 37 degrees).
So these will be most efficient at Sunrise/Sunset. When the sun is at its weakest (lots of atmosphere to get through).
On the other hand, if they are good projection screens, you aim your projector at it, that causes it to generate power which you can use to plug the projector into!! Perpetual energy!!!
or something.
Bottom line:
If they work and don't cost a lot more than regular windows (such that in 10 years they save more in power costs than they cost), then great!
If every house with a decent roof exposure between 10 and 3 has even 4 solar panels on and generated even 20% of their own power, and there was enough to knock 5% of power use down in our country (world?), then it's a win.
There's no need to "go off grid" and raise your own goats for food and knit you're own underwear to use solar.
(Now, if you switch from CRT to LCD, you save having to buy $500 of solar panels...)
Not that I'm a consipracy theorist or anything, but of course it does. That is the US Department of Agriculture after all. And we're talking about what? Corn ethanol? Hmm, corn is an agricultural crop.
Now, take a look at the first two bullet items from their mission statement:
Do you honestly think they'd ruin a perfectly good opportunity for one of the largest food crops in the US by speaking badly of corn derived ethanol? Please...